Lab Chiphttp://dx.doi.org/10.1039/c2lc40191f (2012)

In the field of optofluidics, a number of hurdles currently prevent the practical integration of liquid-state elements into traditional high-speed solid-state photonic systems. Among two most critical are the need for a continuous supply of liquid to the device and the difficulty in shuttling light between the liquid- and solid-state sections. Erica Jung and David Erickson in the USA have now presented an integrated system that solves both of these problems. By establishing a direct coupling between liquid- and solid-state waveguides and employing a fluid recirculation system, their scheme consumes 200 times less liquid than today's state-of-the-art devices. Although too slow to be used for direct signal modulation, this configuration offers a number of important advantages for waveguiding, such as the ability to route light of arbitrary wavelength. Solid-state techniques, in contrast, usually make use of an optical resonance, which narrows the range of wavelengths that can be modulated. The device developed by Jung and Erickson can be operated continuously for over 20 h without performance degradation or the need for liquid replenishment. The researchers say that their system represents an important step towards the development of practical optofluidic photonic systems.